Mercury switch contact structure



Dec. '27, 1949 1, 'Q A 2,492,875

' MERCURY SWITCH CONTACT STRUCTURE Filed March 21, 1947 ulilllllllllll INVENTOR. A94 6' Al'cnae iillliul H Patented Dec. 27, 1949 UNITED STATES PATENT OFFICE MERCURY SWITCH CONTACT STRUCTURE In E. McCabe, Chicago, Ill.

Application March 21, 1947, Serial No. 736,303

4 Claims. 1

The invention relates to mercury switch construction and has reference more particularly to an improved cup holder for the enclosed mercury to mercury make and break type of switch.

In electric switches as above described one of the electrodes of the switch has a cup of insulating material fixedly secured to its outer movable end and said cup contains a small quantity of mercury electrically connecting with the electrode. The other electrode may be continuously immersed in the main body of the mercury within the switch container and as a result of certain operations of the switch the main body of mercury is caused to alternately contact with and separate from the mercury in the cup to make and break the electric circuit. Switches of this character have taken the form disclosed in my Patent No. 1,757,436 granted May 6, 1930 wherein the container is tilted in one position to cause the main body of mercury to overflow the cup and contact with the mercury therein and is tilted in another position to cause separation of the mercury bodies.

To eliminate the necessity of tilting mercury switches to effect an opening and closing of the circuit they have been constructed to include movable switch electrodes which are responsive to magnetic forces so that the container may remain stationary while one or both electrodes are moved to energize electric circuits.

An object of the invention is to improve the magnetically responsive type of switch by the provision of a member or holder for attaching a cup-shaped receptacle to a movable electrode whereby the same may be securely and permanently attached.

Another object is to provide a cup holder of economical construction which may be attached to the cup in a simple manner and without imparting stresses and strains to the cup such as might break or crack the cup.

Another object of the invention is to provide a member in the form of a cup holder which may comprise a continuation of an electrode for supporting a cup-shaped receptacle, said member including expansible portions adapted to interengage with a recessed wall formed in the receptacle adjacent the bottom thereof whereby said receptacle may be readily and securely fixed to its cup holder.

A further object is to provide a cup holder of the character described wherein the expansible portions may be expanded by mechanical means to thereby materially reduce the cost of the as- 2 sembling operation by reducing the time required for such operation.

With these and various other objects in view, the invention may consist of certain novel features of construction and operation, as will be more fully described and particularly pointed out in the specification, drawings and claims appended hereto.

In the drawings which illustrate an embodiment of the invention and wherein like reference characters are used to designate like parts:

Figure 1 is an elevational view, parts being shown in section, of a magnetically actuated mercury switch embodying the improved cup holder of the invention;

Figure 2 is an enlarged plan view of the cup holder;

Figure 3 is a side elevational view of Figure 2;

Figure 4 is a view in side elevation of the cup illustrating the assembled relationship of the holder therewith;

Figure 5 is a plan view in section taken on line 55 of Figure 4 illustrating in detail the position of the holder within the cup preparatory to assembly therewith;

Figure 6 is a plan view of Figure 4, with parts being shown in section, illustrating the position of the holder within the cup after assembly of the parts;

Figure 7 is a view in elevation of a preferred form of tool for expanding the portions of the holder for assembly with the cup; and

Figure 8 is a view in plan of Figure 7.

Referring to the drawings, the switch selected for illustrating the present invention essentially consists of a cylindrical glass tube or container l0 closed at its lower end and which end receives and retains a small body of mercury or other electrical conducting fluid II. The opposite end of the tube Ill seals in said end one or more lead-in wires I2 and I4 and the filling stem I5 is provided for exhausting the air from the tube which stem is thereafter sealed. The lead-in wires may be of any electrical conducting material suitable for scaling in glass and if the material is also not affected by contact with the mercury I l the same may be projected within the interior of the tube to contact with said mercury as in the case of the electrode IS. The other electrode of the switch is identified by numeral l8 and said electrode is movable, being supported from the lead-in wire l2v by a flexible hinge member 20 essentially consisting of two relatively movable sections, one section, namely, 2!, being fixedly secured to the lead-in wire l2, whereas acumen the other section 22 has fixedly secured thereto the movable electrode l8. The hinge member is preferably formed of relatively thin, fiat, spring metal and section 22 is adapted to have a knifeedge bearing on section 2| to facilitate flexing movement of the movable electrode- II. The hinge member is more particularly described and claimed in my copending application serial No. 721,638, filed January 11, 1947 and entitled Electrical switch structure. now Patent No. 2,442,931, issued June 8, 1948. A bracket 24 is fixedly secured to movable electrode i4 and said bracket carries at its free end an armature 24. Said armature is adapted to be actuated by magnetic means such as 25 whereby desired movement is shown in Figures 2 and 3, comprises a handle portion 29 and a spade portion 38, the handle portion being fixedly secured as by welding or brazing to the free movable end of the electrode and the spade portion having location within cup 21 and interlocking with the wall of the cup by means of expansible sections which will now be described in detail.

The spade portion 30 of the cup holder is provided with a pair of elongated slots '3l which form the expansible sections 32, since the metal of the spade portion is severed as at 33, thereby separating one end of each section from the body of the cup holder. The spade portion of the cup holder is formed of metal since the holder constitutes a continuation of the movable electrode i8 and thus conducts the electric current to close the circuit when the mercury in the pool is in contact with the mercury in the cup. The thickness of the metal is such as to provide a cup holder of the desired strength and said metal when once bent preferably has the ability to take a permanent set. This characteristic is desirable since the sections 32 of the spade portion of the holder are expansible in a direction outwardly about the weakened areas 34 located ad'acent the outer ends of the slots 3!, and when once expanded it is necessary for the sections to remain in position. This-expanded position of the sections interlocks the cup holder to the cup as clearly disclosed in Figures 5 and 6. In order to facilitate the interlocking of the expansible sections with the cup the inside wall of the cup adjacent the bottom is for-med with an annular groove 35. The spade portion 30 of the holder is oval in shape rather than circular. This permits a greater lateral movement of the expansible sections into the groove 35 provided therefor, although said movement is not sufficient to cause a fracture at the weakened areas 34 but merely to set the metal as previously described so that the expanded sections will not return.

To avoid injury to the cup when attaching the same to the holder a suitable tool may be employed which in one form may be such as disclosed in Figures '7 and 8. Said tool essentially consists of a base member 38 having the holes 31 for attachment to a support. A pair of shafts and 4i are suitably journa'lled in the base member 36 so as to extend above the base and depend below the same. The extending end of each shaft is provided with plnions 42 and 42, respectively, which have meshing engagement with each other so that the shafts rotate in unison and to a like extent. The depending end of the shafts carries the pins 44, each pin being identical and having a flat camming surface 48 and a semi-circular rear surface 44. The handle 41 is fixed to part 48 constituting a continuation of shaft 4|. Said part 48 between the handle and pinion carries a coil spring 50. said coil spring being fixed at one end to stud 5i and at its other end to part 48. Upon rotation of handle 41, part 48 will be rotated so that rotation of the shafts and thus rotation of the pins 44 will take place. As shown in Figure 8, stud 5| acts as a stop for handle 41. the handle automatically contacting the stop since the handle is yieldingly biased in this direction by the coil spring 50. Movement of the handle 41 is a counterclockwise direction, Figure 8, is limited by the eccentric stud 52. The eccentricity of stud 52 enables adjustment of the same so that the rotation of handle 41 can be confined to proper limits.

In assembling a holder with a cup it is possible to expand the sections 32 of the holder by hand. Any convenient tool such as a screw driver may be inserted in the slots and upon rotation of the same the necessary camming action is produced to expand the sections into the groove 35. However, it is possible to injure the cup should excessive camming action be applied for the purpose of expanding the sections. To prevent this, as well as to provide equal expansion of the sections, a mechanical tool as shown in Figures '1 and 8 has been provided for the correct assembly whereby the camming action of the pins is controLled. Said pins are spaced the proper distance so that they will readily enter the slots 3| and said pins have been formed with thc fiat camming surface 45 directed outwardly. Accordingly, it will be seen that the semi-circular rear surfaces of the pins are directed toward the longitudinalcenter web 53 for rotation thereagainst. The web provides a brace effect to give support to the pins during the camming action. In such action the forces applied by the pins in expanding the sections are against the center web and, with rotation of the pins controlled, the cup may be thus relieved of strains which might otherwise be applied thereto. Upon rotation of handle 41 in a counterclockwise direction, Figure 8, the pins will be rotated, at least to an extent where sufficient camming action is applied to the sections 32 to cam them outwardly into groove 35.

The invention is not to be limited to or by details of construction of the particular embodiment thereof illustrated by the drawings, as various other forms of the device will of course be apparent to those skilled in the art without departing from the spirit of the invention or the scope of the claims.

What is claimed is:

- 1. In an electric switch, the combination with an electrode, of a cup of insulating material supported by said electrode, the supporting means for thecup including a flat portion at the end of said electrode having a pair of laterally expansible sections and a central web to which the expansz'ble sections are secured, said fiat portion having location adjacent the bottom of the cup, and said cup having a recess formed in the inside wall thereof for receiving the expansible sections when they are expanded later- 7 ally in a direction outwardly from the center web.

2. In a mercury switch, the combination with an electrode, of a cup of insulating material supported by said electrode, the supporting means for the cup including a flat spade-shaped portion at the terminal end of the electrode and being located within and adjacent the bottom 01' the cup, said flat portion having spaced slots formed therein on the respective sides of a 10 acterized by their ability to remain set in ex- 20 panded position.

4. An electric switch as defined by claim 2, wherein the pair of expansible sections are characterized by their ability to remain set in their expanded position.

IRA E. McCABE.

REFERENCES CITED The following references are. of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,441,275 Gi-ttelsohn Jan. 9, 1923 1,937,746 Cramblet Dec. 5, 1933 1,949,915 McCabe Mar. 6, 1934 FOREIGN PATENTS Number Country Date 467,124 Germany Oct. 20, 1928 

